Data recording disk drives, such as magnetic disk drives, store information on concentric tracks of a data surface of a rotatable magnetic recording disk. A slider rides on an air bearing generated between the rotating disk data surface and a transducer on the slider and reads data from and writes data to the data surface. The transducer slider is attached to a flexure of a suspension and is moved generally radially from track to track by an actuator. The suspension typically includes a load beam which is attached to an arm of the actuator, and the flexure. While the disk rotates, the load beam provides a resilient spring action which supports the flexure and slider against the air bearing, and the flexure allows the slider to gimbal to adjust its orientation for unavoidable disk surface flatness variations, while maintaining the transducer in a close relationship with the disk surface. Specifically, the flexure provides controlled flexibility in pitch and roll motion of the slider relative to its direction of motion on the rotating disk surface, and resistance to yaw motion so that the transducer will maintain a constant radial position.
The transducer typically includes separate write and read heads, each requiring two electrical leads for interconnecting the transducer with an electronics module which includes a write and a read channel. The electronics module may comprise separate electronic components distributed throughout the disk drive. One type of suspension is a composite or laminate structure including a flexure, for example of a thin stainless steel, with electrical insulation and patterned electrical leads formed thereon, commonly called an integrated lead suspension. The patterned electrical leads for the heads are routed along the actuator arm, load beam, and/or flexure and may briefly separate from the flexure and are routed to the slider for connection to the transducer. The slider is mechanically attached to the flexure, and the patterned electrical leads are electrically connected to terminations for the four electrical leads of the write and read transducer. Assignee's copending U.S. Patent application Ser. No. 08/726,116, filed Oct. 4, 1996, describes examples of such integrated lead suspensions for providing a mechanical connection for the slider and electrical connections for the transducer, all of the electrical leads supported by a flexibly connected extension to the flexure.
The disk drive actuator typically comprises a linear or rotary voice coil motor which moves the actuator arm and the attached suspension and slider to position the transducer at the desired track of the data surface, and, under the control of a servo control system, to utilize servo information on the data surface to closely follow any runout or other radial displacement of the track as the disk is rotated. As the tracks are made thinner and placed closer together (in order to increase the density of the tracks and thereby the data capacity of a disk surface), it becomes increasingly difficult for the actuator and the servo control system to quickly and accurately position and the transducer over the desired track and to provide track following. For example, a servo control system with a voice coil motor will have difficulty achieving a servo loop bandwidth greater than 1 KHz.
Micro-actuators have been proposed for attachment to the suspension to provide a fine positioning of the transducer while the actuator provides a course positioning. Examples of micro-actuators are shown in U.S. Pat. No. 5,657,188 and in U.S. Pat. No. 5,189,578. The micro-actuators of the patents are shown as being located on the load beam and the actuator arm, respectively, but a better location is between the flexure and the slider so that the micro-actuator does not have to move the mass of the load beam and suspension in addition to that of the slider.
A difficulty in locating the micro-actuator between the flexure and the slider is that the micro-actuator requires wiring for operation with a servo control system. This wiring is in addition to the wiring required for the write and read heads of the transducer, and needs to be provided in the same limited space without adversely affecting the stiffness of the flexure.
The mechanical attachment of the micro-actuator and of the slider to the flexure must be at a correct orientation with limited residual stress to assure that the slider will approach the disk surface at the correct orientation so that it will generate the needed air bearing. Along with adhesive bonding of the micro-actuator to the flexure, a large number (typically 8 or more) of electrical leads must also be connected to the micro-actuator and to the transducer. This large number of leads at one end of the slider will have a number of individual misalignments with the associated terminals, which accumulate and cause forces and moments tending to alter the pitch and roll static attitude of the suspension.
It may be possible to force the termination lead platforms into alignment, but once the adhesive is cured, and the suspension is taken out of the fixture, the spring back forces may bias the pitch or roll static attitude of the suspension.
Thus, in either case, the slider may approach the disk surface at an incorrect orientation so that it will not generate the needed air bearing.